Remove @file tag docblock

As per coding standard documentation at 'https://www.drupal.org/coding-standards/docs', @file tag docblock should not be there in the files that contain a namespaced class/interface/trait, whose file name is the class name with a .php extension.

The @file doc block MUST be present for all PHP files, with one exception: files that contain a namespaced class/interface/trait, whose file name is the class name with a .php extension, and whose file path is closely related to the namespace (under PSR-4 or a similar standard), SHOULD NOT have a @file documentation block.